JPH0691322B2 - Ceramic multilayer wiring board - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic multilayer wiring board that constitutes a circuit used in electronic devices and the like.

2. Description of the Related Art In recent years, ceramic multilayer wiring boards have been used to densify circuits in electronic devices and the like. When a capacitor is formed on the ceramic multi-layer wiring board, in the high-temperature firing alumina-based multi-layer wiring board having a firing temperature of about 1500 ° C. as shown in FIG. 1 is multi-layered, and a conductive pattern portion 2 used as a conductive path is formed between the layers by a conductive layer made of tungsten, molybdenum, or the like that needs to be baked in a reducing atmosphere to prevent oxidation, and a part of the conductive layer is formed. Are arranged as electrodes 3 so as to face each other with the dielectric layer 1 interposed therebetween to form a capacitor. However, in the case of this alumina-based multilayer wiring board, there is a problem that a large-capacity capacitor cannot be formed because the alumina-based ceramic forming the dielectric layer 1 has a low relative dielectric constant. To solve this problem, it is not necessary to form a large-capacity capacitor as shown in FIG. 3, and the conductive pattern portion 4 as a conductive path is formed.
The insulating layer 5 that forms the electrode is an alumina-based ceramic, and the dielectric layer 7 that forms the electrode 6 is required for a large-capacity capacitor.
Can be a multilayer wiring board made of ceramic having a perovskite structure containing barium titanate or lead. However, such a multilayer wiring board has
1500 ° C because it uses alumina ceramic
It is necessary to perform firing at a high temperature to a certain degree, and it is necessary to perform firing in a reducing atmosphere because the conductive pattern portion 4 and the electrode 6 are formed of tungsten, molybdenum, or the like. However, the ceramic having a perovskite structure containing barium titanate or lead has a problem that the insulation resistance is remarkably reduced and the function of the capacitor is lost as it is fired in a reducing atmosphere at a high temperature. Therefore, as a countermeasure, a glass ceramic is used instead of the alumina-based ceramic used as the insulating layer 5, and a material such as a silver-palladium alloy is used instead of the tungsten or molybdenum used as the conductive pattern portion 4 or the electrode 6. A multilayer wiring board in which a ceramic having a perovskite structure containing barium titanate or lead is used as the dielectric layer 7 and is fired at about 900 ° C. is considered.

Problems to be Solved by the Invention However, in the above-mentioned configuration, since the insulating layer 5 and the dielectric layer 7 are different materials, there is a problem that warpage or deformation occurs due to firing. When copper is used as the electrode 6, it is necessary to fire it in a reducing atmosphere in order to prevent oxidation, but a ceramic having a perovskite structure containing barium titanate or lead used as the dielectric layer 7 is used. There is a problem in that the function as a capacitor is lost due to a significant reduction in insulation resistance due to partial reduction due to firing in a reducing atmosphere. The present invention can solve the above problems and provide a ceramic multilayer wiring board in which a high quality capacitor is formed by a simple method.

Means for Solving the Problems The ceramic multilayer wiring board of the present invention has an insulating layer composed of a mixture of glass ceramic and alumina-based ceramic, a glass ceramic having the same composition as the glass ceramic, and a ratio higher than that of the alumina-based ceramic. A capacitor is formed by laminating a dielectric layer composed of a mixture of ceramics having a high dielectric constant and disposing electrodes facing each other with the dielectric layer interposed therebetween.

Action The ceramic multilayer wiring board of the present invention, in which the insulating layer and the dielectric layer are each composed of a mixture containing the same quality of glass ceramic, the shrinking process during firing is similar and there is no warpage or deformation even after firing. Becomes Further, as for the capacitor capacity, it is possible to obtain a larger capacity than that of the conventional alumina-based multilayer wiring board.

EXAMPLE Hereinafter, a ceramic multilayer substrate of an example of the present invention will be described with reference to FIG. In FIG. 1, the insulating layer 8
Is composed of a mixture of a lead borosilicate glass ceramic 9 and a filler component 10 composed of an alumina ceramic,
The dielectric layer 11 is composed of a glass ceramic 12 having the same composition as the glass ceramic 9 and a filler component 13 made of a ceramic having a perovskite structure containing at least barium titanate or lead. The conductor layer composed of the conductive pattern portion 14 and the electrode 15 is silver or copper, and the electrode 15 is provided so as to face each other with the dielectric layer 11 in between to form a capacitor. The above is the ceramic multilayer wiring board after firing at 900 ° C. in air or in a reducing atmosphere such as nitrogen. Next, a process for producing the ceramic multilayer wiring board before firing will be described.

The green sheet to be the insulating layer 8 is created as follows. A lead borosilicate glass powder having an average particle size of about 1.8 μm and an alumina ceramic having an average particle size of about 1.8 μm as the filler component 10 are mixed at a weight mixing ratio (hereinafter referred to as a mixing ratio).
45:55 powder is made into a green sheet using an acrylic binder. Further, the green sheet that becomes the dielectric layer 11 is created as follows. Lead borosilicate glass powder having the same composition as that of the glass ceramic 9 used in the insulating layer 8 and having an average particle size of about 1.8 μm, and titanic acid having a filler component 13 having an average particle size of about 1.2 μm and a relative dielectric constant of about 5000. Barium powder, or an average particle size of about 1.5 μm and a relative dielectric constant of about 5000
A ceramic powder having a perovskite structure containing lead is mixed at a mixing ratio of 45 to 55 to form a green sheet using an acrylic binder. After that, silver or copper is printed as the conductive pattern portion 14 and the electrode 15 on each green sheet of the insulating layer 8 and the dielectric layer 11, and after drying, a total of four green sheets are laminated to form a multilayer. is there. Next, Table 1 shows a list of material combinations examined this time. In the table, A, B, C, D are A ... Lead borosilicate glass powder, B ... Alumina ceramic powder, C ... Lead-containing ceramic powder having a perovskite structure, D ... Titanium. It is barium acid powder.

And among the sample numbers 1 to 4 shown in Table 1, the sample number 1
No. 2 is fired in air at 900 ° C, and sample Nos. 3 and 4 show the characteristics of the multilayer wiring board after fired in a nitrogen atmosphere at 900 ° C.
Shown in. Sample numbers 1 to 4 in Table 2 are sample numbers 1 in Table 1.
Corresponding to ~ 4, IR is insulation resistance, unit is Ω · cm, ε is relative permittivity, tanδ is dielectric loss tangent, ε
And tan δ are measured at 10 KHz.

As shown in Table 2, the warp / deformation of the conventional ceramic multilayer wiring board which has been a problem has been solved by providing the insulating layer 8 and the dielectric layer 11 with glass ceramics 9 and 12 having the same composition, respectively. Further, the fired insulating layer 8 has a form in which the fired filler component 10 is scattered in the fired glass ceramic 9, and the fired dielectric layer 11 is in the fired glass ceramic 12. The fired filler components 13 are scattered. Therefore, since the dielectric layer 11 has a large relative dielectric constant, a large capacity capacitor can be formed. The ceramic having a perovskite structure containing lead and barium titanate used in this example had a relative permittivity of about 5,000.
There are ceramics and barium titanate having a perovskite structure containing 000 to 20,000 lead, and using these materials, the relative dielectric constant of the dielectric layer 9 can be further increased.
Further, when copper is used for the conductor layer composed of the conductive pattern portion 14 and the electrode 15, it is necessary to perform firing in a reducing atmosphere. However, when a conventional dielectric material is fired at 900 ° C. in a reducing atmosphere, insulation resistance is increased. It was not possible to use copper for the conductive pattern portion 14 and the electrode 15 because the function was significantly lowered and the function of the capacitor was lost. However, in the dielectric material of the present invention, since the filler component 13 is shielded from the reducing atmosphere in the glass ceramic 12, the filler component 13 is less affected by the reduction and does not lose the function of the capacitor.
It can be used for the conductor layers of 14 and electrode 15. Further, it is known that the warpage and the deformation are eliminated even when the ratio of the glass ceramics 9 and 12 in the insulating layer 8 and the dielectric layer 11 is 35 to 65%, respectively. Needless to say, the ratio may deviate from the above value depending on the conditions such as the material and composition of the glass ceramics 9 and 12 and the filler components 10 and 13 and the firing temperature.

EFFECTS OF THE INVENTION As described above, according to the present invention, the insulating layer is made of a mixture of glass ceramics and alumina-based ceramics, and the dielectric layer has a relative dielectric constant higher than that of the glass ceramics and alumina-based ceramics having the same quality as the insulating layers. Since it is composed of a mixture of high ceramics, there is no warpage or deformation due to firing,
In addition, a large capacity capacitor can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional side view of an essential part of a ceramic multilayer wiring board according to an embodiment of the present invention, FIG. 2 is a sectional side view of an essential part of a conventional ceramic multilayer wiring board, and FIG. 3 is another conventional ceramic multilayer wiring board. It is a principal part sectional side view of a board | substrate. 8 ... Insulating layer, 9,12 ... Glass-ceramic, 10, 13 ...
Filler component, 12 ... Dielectric layer, 14 ... Conductive pattern part, 15 ... Electrode.

Claims (2)

[Claims] 1. A dielectric layer composed of an insulating layer made of a mixture of glass ceramic and alumina ceramic, and a mixture of a glass ceramic having the same composition as the glass ceramic and a ceramic having a relative dielectric constant higher than that of the alumina ceramic. A ceramic multilayer wiring board in which a capacitor is formed by laminating a body layer and disposing electrodes facing each other with the dielectric layer interposed therebetween. 2. The ceramic multilayer wiring board according to claim 1, wherein the electrode is copper.